Windmills have been used traditionally for pumping water directly from wells to livestock watering troughs or for dewatering low areas to prevent flooding. Their economical use for driving deep well irrigation pumps has not yet been demonstrated. To drive a pump of the size that is normally used for irrigation would require an uneconomically large windmill for wind velocities in 8 to 12 mph range. For example, to lift water 225 feet with an 82% efficient pump and piping system at a rate of 600 gpm would require an input of 41.5 horsepower and a two blade propeller type windmill approximately 126 feet in diameter. A windmill designed for continuous irrigation pump operation in fresh breeze (19-24 mph) or a strong breeze (25-31 mph) would be one fourth as large or approximately 30 feet in diameter. Because of the low horsepower that would be generated by a 30 foot diameter windmill at 10 miles per hour (2.3 hp), some means of energy storage would be required for operating the pump in low velocity wind.